A gas turbine engine generally includes a compressor section, a combustor section, a turbine section and an exhaust section. In operation, the compressor section may induct ambient air and compress it. The compressed air from the compressor section enters one or more combustors in the combustor section. The compressed air is mixed with the fuel in the combustors, and the air-fuel mixture can be burned in the combustors to form a hot working gas. The hot working gas is routed to the turbine section where it is expanded through alternating rows of stationary airfoils and rotating airfoils and used to generate power that can drive a rotor. The expanded gas exiting the turbine section may then be exhausted from the engine via the exhaust section.
It is known that the maximum power output of a combustion turbine is achieved by heating the gas flowing through the combustion section to as high a temperature as is feasible. The hot gas, however, heats the various turbine components, such as airfoils and ring segments, which it passes when flowing through the turbine section. One aspect limiting the ability to increase the combustion firing temperature is the ability of the turbine components to withstand increased temperatures. Consequently, various cooling methods have been developed to cool turbine hot parts.
In the case of ring segments, ring segments typically include a cavity supplied with high pressure air which passes through an impingement plate to provide impingement cooling to a ring segment panel. Longer ring segments may be provided with a middle support hook located between forward and aft support hooks, dividing the high pressure cavity into two cavities, one on each side of the middle support hook. The high pressure air can be provided to each of the two chambers to cool the panel, such as is disclosed in U.S. Pat. No. 8,353,663.